Putin has been widely credited for bringing security and some semblance of order to Russia after the turbulent decade that followed the collapse of the USSR, however, this attack may shatter some of that confidence.

Russia on Saturday said it had arrested 11 people -- including four gunmen -- over the attack on a Moscow concert hall claimed by the Islamic State, as the death toll rose to 115.

Gunmen who opened fire at a Moscow concert hall killed more than 60 people and wounded over 100 while sparking an inferno, authorities said Saturday, with the Islamic State group claiming responsibility